Amplifying relay system



April 16, 1935. H. GEFFCKEN 1,998,131

AMPLIFYING RELAY SYSTEM Filed June 23, 1950 2 Sheets-Sheet l E51. 1. r10 fin a.

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April 16,1935. I GEFFCKEN 11,998,131

AMPLIFYING RELAY SYSTEM Filed June 23, 1930 2 Sheets-Sheet 2 WW wax W Patented Apr. 16, 1935 UNITED STATES PATENT OFFWE AMPLEYING RELAY SYSTEM Application June 23, 1934i, Serial No. 463,211 in Germany June 25, 1929 13 Claims.

My invention relates to novel apparatus for and methods of operating electrical circuits, and more particularly, relay systems in which small current variations are-used for operating relay devices.

In regulating systems using electron tubes, the response obtainable is limited to a pre-determined minimum variation of potential applied across the input of the tube. Applications of potential variations less than this pre-determined minimum variation will not be sufficient to operate a receiving device connected to the tube.

I have discovered that if the available potential variations, instead of being applied across the grid of the electron tube, are applied to vary the heating of the filament, potential variations less than the above mentioned minimum are sufficient to produce large enough current variations in the relay device to operate a receiving device.

Accordingly, an object of my invention is to provide a novel method of and apparatus for operating regulating systems.

A further object of my invention is to provide a novel method of and apparatus for operating electron tube relay devices.

A still further object of my invention is to provide a novel apparatus for a method or" rendering a relay system responsive to very slight potential variations.

Still another object or my invention is to provide a method of operating a relay device which comprises applying potential variations to vary the heating of the filament of an electron tube relay device.

I have also discovered that by applying the slight potential variations available to vary the heating of the filament of a three-electron tube, a substantially large difference of potential may be obtained in the output circuit of such a tube, due to the tube resistance. This large potential variation will then be utilized in an amplifying circuit in a well known manner.

Accordingly, a further object or" my invention is to provide novel methods of and apparatus for producing wide voltage variations in accordance with very slight voltage variations for operation of relay devices.

In the operation of an electron tube as a relay device, it is desirable to prevent the accidental operation thereof in response to normal slight potential variations. By applying the controlling potential variations to vary the heating current of the filament, the inertia of the filament will voltage of saturation, for example, 100 volts.

(Cl. Mil-32%) prevent any accidental operation in response to these normal impulses.

Accordingly, a further object of my invention is to provide a method of and means for preventing false operations in relay systems.

Mechanical relays which are to respond to relatively weak currents require a high ohmic resistance winding, which in turn introduces. serious problems of potential variations there-across, as the current flow is varied. This difriculty is avoided in the present invention, since the electron tube is only slightly influenced by the potential drop of the receiving device resistance.

Further objects of my invention will be clear from the detailed description of the invention, which follows in connection with the drawings, in which:

'Fig. 1 shows the characteristic curve of a heated filament.

Fig. 2 is a circuit diagramzof connections in accordance with one embodiment of my invention.

Fig. 3 is a circuit diagram of my invention showing the system operated for actuating a relay.

Fig. i is a circuit diagram of my invention ap- H plied to operating a recording device.

Fig. 5 is a circuit diagram of the invention applied to alternating current.

Fig. 6 is a circuit diagram of a further modification of my invention.

In Fig. l, I have shown the electron emission characteristic curve of a filament of an electron tube in which the abscissa is the heating current llii in milliamperes and the ordinate is the resultant electron current flow in nu'croampe'res at the As will be noted, there is no electron emission until approximately 60 milliamperes heating current is supplied, but thereafter there is a very rapid rise in the emitting current for slight changes in heating current, up to a saturation point (not shown). The formula for this curve has been found to be:

ie=7cih in which L: is the electron emitted current; in is the heating current, both measured in millimperes, and k is a constant with the value 10 As will be clear from the curve, and as can be determined from this formula, the emission, and. consequently also the voltage drop in the electron tube, when it is connected in series with a resistance and when the anode voltage is properly selected, varies very widely in response to slight fluctuations in the value of the heating current.

This wide variation in the electron emission may then be utilized for operating relay devices, as in the manner about to be explained.

In Fig. 2, circuit connections are shown in which a relay device is operated in accordance with my invention. A heating filament l in the vacuum tube 2 serves as an emitter of thermionic electrons. Connected in series with this electronic tube 2, is a resistance 3. The voltage drop across resistance 3 varies in accordance with the electron stream flowing in the tube 2 and in turn controls the potential at the point G.

Connected to point (i is the resistance 6. The resistance 6 and condenser l are inserted for purposes of increasing the safety of operation of the glow tube 5. Connected in series with the glow tube 5 is a mechanical relay diagrammatically illustrated at 8, for performing any switching operation.

The resistance 3 connected in series with the electron tube may be chosen very high, so that the switching operations may take place at very slight increase in the emission current of tube 2.

in any well known manner, as by means of a battery 9 as shown and the controlling heating current may be applied to terminals 9' in series with the cathode heating circuit. Preferably the heating filament l is so chosen that it will be rendered emissive at slight voltages and current intensities.

When the current flow through the filament i is sufficient to produce an electron current in the tube 2, the potential at point 41 is lowered and in turn controls the grid electrode of the glow discharge tube 5, to prevent a discharge in the tube 5. When, on the other hand, the electron current flow in tube 2 is stopped by reason of a decrease in the heating current through the filament i, the potential at point t is raised, in turn correspondingly raising the potential of the grid of the tube 5 and producing a discharge in the tube, which, in turn, controls the operation of the relay 8.

Although the arrangement illustrated in Fig. 2

may control any operation in accordance with slight voltage variations, producing changes in temperature of the filament i for the purpose of regulation, the system is also applicable to the control of a relay sensitive only to largerfluctuations of potential, such as about 5 volts, which are produced in response to slight variations of voltage of the heating current to the filament i.

Fig. 3 shows an improvement for operating a relay in response to very small variations of voltage. According to this figure,-the heating filament I of the electron tube 2 is preheated to a point approximately where the electron emission begins to take place, by means of a battery 9 connected to a series resistance In.

The controlling potential fluctuations are superimposed on the heating current, so that its absolute value will merely appear as a variation battery 9 flows over the resistance i2. By proper adjustment of the resistance H, the voltage drop occurring therein may be made equal to the voltage drop of the heating filament I. Consequently, the terminals I3 and i i are maintained at equal potential and the controlling potential variations applied at terminals 13 and I l are of maximum effectiveness.

With this connection, a bridge circuit may be arranged, since it will in no way interfere with the circuit connection to which it is associated when in normal condition.

In the example shown in Fig. 3, the electron tube 2 is connected in series with the resistance 85. The potential variations occurring thereat in accordance with variations in electron current flow of the tube 8 are applied to the grid of amplifying tube I6. A relay device diagrammatically shown at l? is in turn connected in the output circuit of the tube 66.

In utilizing my proposed system, it is desirable at times to connect in series the electron tube 2, a discharge tube and a condenser connected in parallel therewith. A periodic discharge of the tube may thus be obtained by means of which it is possible to measure currents in a.Wheatstone bridge circuit, or an electro-mechanical relay such as a telephone relay, may be operated.

Fig. 4 illustrates a recording or controlling device which operates in connection with a Wheatstone bridge. As herein shown, two electron tubes 08 and H! are provided with heating filaments 20 and 2| and connected in series, through which current flows in opposite direction from a source of heating supply 22. The pre-heating currents,

are adjusted by means of resistances 23 and 24 to the desired value. Potential variations from a standard Wheatstone bridge 21 are applied over the terminals 25 and 26 to the filament circuits.

A bridge current flowing from point 25 to point 26, for example, will increase the heating current in the filament 20 of tube i8 and decrease the heating current in the filament 21! of tube IS. AS a result, the emission of the electron tube l8 will increase; while the emission in tube i9 will decrease. By the arrangement of the device which operates in accordance with the difierence in the electron emission of these two tubes, a considerably amplified control of the Wheatstone bridge is obtained.

Inasmuch as by the system herein disclosed, large variations of voltage can be obtained, it is also possible to make use of the so-called accumulating device. As shown in; Fig. 4, two discharge tubes 28 and 29 are connected to the output circuit of tubes 18 and i9 respectively and are bridged by condensers 30 and 3|. The anode voltage is supplied by the battery 32.

When the electron current flows, the condensers 30 and 3! will become charged until break down potential for the discharge tubes 28 and 29 is obtained. The potential of these discharges depends on the intensity of the electron current flow. Normally, it is chosen of equal value for both discharge tubes, by means of suitable preheating of'the tubes l8 and IQ and by the adjustment of condensers 38 and 3 l In consequence, difierences of frequency will be detected, if by the occurrence of bridge currents, the emission of the. two tubes diifers. Thus, bridge currents willbecome manifest by difierence of frequency, whereby at the same time, the direction of the bridge currents will become noticeable. In the present example, a novel arrangement is disclosed for applying this cumulative method to the discharge tubes. As is known, a discharge tube will discharge after emission has been initiated, merely up to its so-called extinguishing potential, which lies about from In to volts below its ignition potential. The dis,- charging energy set free which can be increased by increasing the dimensions of the condensers 30 and 3| is reduced, on the one hand, by the inper resistance of the discharge tube, and on the other hand, by the difference of potential re ferred to.

Accordingly, the control of relays is rendered difiicult and in Fig. 4, relays 33 and 34 are arranged for the purpose of increasing the output of the system, through which relays the groups of contacts 35 and 36 are actuated. As soon as a discharge occurs in the tube 28, for example, relay 33 is energized and the latter will in turn close the contacts 35. Condenser 3b is thereupon discharged through the relay 33. In this manner, the total electrical energy which'is accumulated in the condensers so and 3!] is utilized, through the energization relays 33 and 3d and resultant operation of gear 3i in response to this energization.

A further advantage of this practice resides in the fact that by the complete discharge of the two condensers till and ill, the initial potential of the same will become equal for both and equally defined for each, so that errors in the charging potential which would naturally occur, will be avoided.

The relay 38 will operate in an analogous manner to the operation of relay as described above, with the difierence, however, that upon actuation of the operation of relay the gear ill is advanced in the opposite direction. The gear 37! serves, for example, for influencing that eiiect, variations of which, from a pre-determined source control the bridge connection 2?, as, for example, a chemical process or variable branch of the bridge 2?. The connection indicated will cause an automatic indication record and control or" the said efiects, since the gear Bl is only advanced to one side, if, by the occurrence of a bridge current, an irregularity in the charging time of the two circuits is produced. In the example according to Fig. 4, considerable difference of potential will occur in the anode cir cult of the tubes 23 and t9 (the condenser will charge from the zero potential up to the value of the ignition potential of the discharge tubes 8 and 29), so that it appears advantageous to bias grids 3B and 39 in the electron tubes it; and i9 respectively. A constant bias potential is accordingly applied, in order to forcibly obtain as constant a saturation current as possible.

A still further advantage of this method and circuit resides in the fact that it can be employed in equal manner for direct current or for alter hating current and that the frequency of alternating current will be without any principal in= iiuence on the mode of operation of the circuit. It is even possible to obtain the bridge, preheating current and anode voltage from a corn mon source of alternating current.

The thermionic inertia of the heating filament is such that the phase of the anode alternating voltage may be arbitrarily displaced toward the phase of the heating voltage. Furthermore, combinations of alternating currents and direct currents may be employed in this system.

It will now be clear that a regulation system is here obtained which is extremely sensitive both to variations and the rate of variation and operates instantaneously to restore the condition to its Dre-determined value. I

The application of alternating current to my invention is illustrated in Fig. 5. As here shown, a bridge 40 of the alternating current type is the controlling source. Electron tubes M and 42 are provided with filaments 35 and 36 respectively, which are preheated from energy obtained from an alternating current source through the transformer 3. The transformer it which connects the bridge Ml to the system is provided with a mid-point tap tothe transformer 32-3, so that it ofiers no inductive resistance to the heating current. This heating current now flows through the secondary of the transformer 3 3 to the filaments l5 and 56 in opposite direction.

The series resistance Ll'l serves for the adjustment of heating and for the fine adjustment or compensation of the voltage drops occurring in the heating filaments t5 and 66.

By reason of the connection of the bridge M! through the transformer 36 to the filaments and it, variations in the bridge current will act to increase the heating current of one tube and reduce the heating current of the other tube. In the present arrangement, it would be obvious that it is necessary to have the frequency of the heating current equal to the frequency of the bridge current.

This arrangement may also be used for controlling the frequency or phase of currents in generators, since both tubes ll and 32 will show differences of emission only with a frequency coincidingwith the pre-heating frequency. This difference of emission is brought about by changes in the phases or amplitudes of the additional currents. On the other hand, with differences in frequency between the heating current and the impressed current, the emission of both tubes is changed uniformly or fluctuated periodically and respectively.

As in the case of th direct current systems as described hereinbeiore, the controlling current may also be connected to the terminals ill and G9. In this case, the cholze coil formed by the winding of the transformer G 3 situate in the heating circuit must be ma ntained. or be re-' placed by a resistance, since, otherwise, the current to be detected would flow over this circuit, instead oi through the heating filament.

The anode voltage for the tubes di and :12 is applied to the transformer and condensers and are provided for the accumulation of electron currents, as described. hereinbeiore. A

switching system is employed consisting of three switches, 53, 5:3 and which will. periodi ally carry out three switching operations, as described hereabove. The switch is normally closed and the switches and 53- are open; that is, in their central position, as shown. As a result, the circuits for condensers 5i and are closed and these condensers will become charged at various voltages in accordance with th current flowing in the tubes ll and 32. It, now, switch 55 is opened and at a pre-determined interval thereafter, switches and lid are connected with terminals and 577, an impulse of the compensating current would flow by way, of resistance 53 and from one electrode oi the condenser which has received the larger charge, to the opposite electrode or" the other condenser which has received the smaller charge. This charging cur rent is used to control the amplifying tubes 62 and 63.

The switches 53 and 56 will immediately after these have been in engagement with the contacts 56 and 571, beiswitched over to engaged contacts t0 and El and, both condensers will thereupon discharge over their individual short-circuiting-path. Switches 53 and 541 will thereafter again'resume, a position of rest in the midposition, as shown, and the charging of condensers 5i and 52 may now be resumed. The actuation of switches 53, 56 and 55 takes place automatically at pre-determined intervals, as, for example, by a clock control.

Referring now again to the discharge current flowing from condenser E! or 52 over the switches 53 .and 56 in engagement with contacts 56 and 57, it will be noted that this current flows through the resistances 58 and 59. Accordingly, the grid of the amplifying tube 62 will be subjected to a temporary positive charge by way or the condenser til, while the grid oi the tube 53 is subjected to a temporary negative,

charge by way of condenser 65. If, new, the grids of both tubes 52 and as are provided with sumciently high leakage resistances, the grid of tube 62 will retain a negative charge for apredetermined interval; while the grid of tube 53 in which only a negative impulse has been impressed will again assume a period of rest after the termination of this impulse.

The anode current of the tubes 62 and t3 supplied by the battery 6% will now difier in accordance with the potentials applied to the next grids and this difierence in anode current flow controls the operation of a difierential relay bl, which may release any desired switching operation.

In 6, I have shown a further modification of my invention, in which the pro-heating current for the ents and the bridge currents are combined. It will. be assumed that it is desird to measure the resistances 68 and cc. These are connected in parallel through the resistance id to a source of alternating current, or, if preferred, to a source of direct current.

Connectedin'series with each of the resistances 58 and are the filaments of thermionic electron tubes ii and i2. The-connections of the anode circuits of these thermionic electron tubes iii and Ware not described in. this example, since they maybe arranged in a manner analogous to that of the examples given heretofore. The circuit arrangements are such that the heating filaments are situated at the negative end of the series connection and the bridge voltage may therefore serve as anode voltage for the tubes ii and 72. The adjustment to the highest degree of sensitivity is efiected by means of the variable resistance iii and small resistances not shown, connected in parallel with the heating filaments.

It will be obvious with alternating current arrangements, it is possible to couple the heating filaments of tubes H and 32 through transformer with the resistance circuits 68 and to, so that the tubes ii and 72 may be arranged as desired, as, for example, with both electron path streams v connected in series to obtain a high potentiometer eiiect.

By means of the arrangement hereinbeiore described, small variations in voltage are translated into large variations in voltage, controlling tube voltage, step relays and the like, wherein the amplification of energy, above all, is of secondary importance.

Large variations of potentials are obtained by.

connecting in se the thermionic electron.

tubes with a supply of current at saturation, for example, with an electron tube which is constantly heated. As mentioned above, all such connections may be carried out with alternating current and indirectly heated cathodes. With the new circuit arrangements herein described,

it is possible to use as a controlling current, the.

heating current, bridge currents, detector and other rectified currents, and to transform these into variations of potential.

An increase of emission of thermionic electrons can be eiiected by filling the tubes with gas. If the gas pressure is properly chosen, luminous discharges are possible at the critical voltages and the thermionic electron stream then functions at the same time as a discharge step relay.

Although I have illustrated my invention in.

connection with various adaptations thereof, it will be clear that it has other uses and I do not intend to limit myself by these specific examples, except insofar as set forth in the appended claims.

I claim as m invention:

1. An electrical system, in combination, a control relay, a pair of thermionic discharge devices including cathode and anode electrodes; an impedance connected in series with each of said discharge devices; a source of potential supply connected to said devices in series with their respec tive impedances; means for preheating said cathodes to a predetermined emitting temperature; means for applying additional heating current to said cathodes in opposite direction in accordance with input signals; and means for utilizing the difference of output current of said devices for controlling said relay.

- 2. In an electrical system as claimed in claim 1 in which said cathodes form the arms of a balanced bridge circuit completed by a pair of impedances forming the remaining bridge arms; a

common cathode heating battery connected in one of the diagonal branches of said bridge; and means for applying input potential to the remaining diagonal branch of said bridge system.

3. In an electrical system as claimed in claim 1 in which said cathodes are normally heated to the same emitting temperature.

e. In an electrical system as claimed in claim 1 in which said impedances are comprised each of a gas discharge tube shunted by an electrical condenser.

5. In an electrical system as claimed in claim 1 in which said impedances are comprised of glow discharge tubes shunted by electrical condensers; and a translating device controlled by the discharge current of said condensers.

6. In an electrical system, in combination, a pair of thermionic discharge devices each including cathode and anode electrodes; a common source of potential supply for said discharge devices; means for preheating said cathodes to a predetermined emitting temperature; means for applying additional heating current to said cathodes in opposite direction in accordance with input.

wearer and said resistance being in series, means for preheating said cathode to a predetermined emitting temperature, and further means for applying input currents of low voltage and relatively high intensity to produce additional heating of said cathode for producing currents of high-voltage and relatively low intensity through said resistance.

8. In combination, a source of weak control potential, means for setting up controlling currents by said potential of relatively high intensity and further means for transforming said currents into output currents of relatively high voltage and low intensity comprising a discharge device including a thermionic cathode and an anode electrode; a high ohmic resistance; a high potential supply source; said device, said resistance and said high potential source being in series,

' means for heating said cathode by said control potential and means for utilizing the output voltage drop supplied fromsaid resistance.

9. In combination, a source of weak direct current control potential, means for setting up controlling currents of said potential of relatively high intensity and further means for transforming said currents into currents of relatively high voltage and low intensity comprising a discharge device having a thermionic cathode and an anode electrode; a high ohmic resistance and a high potential source, said device, said resistance and. said high potential source being connected'in series; means for preheating said cathode to a predetermined emitting temperature; further means for additionally heating saidcathode by said control potential, said resistance being of such value as to produce high voltage drop relative to the current therethrough; and means for utilizing the voltage drop supplied from said resistance.

10. In combination, a source of weak direct current potential, means for setting up controlling currents by said potential of relatively high intensity and further means for transforming saidcurrents into currents of relatively high voltage and low intensity comprising a discharge device having a thermionic cathode and an anode electrode, a balanced bridge system consisting of three impedance arms and said cathode as the fourth arm, a source of heating current connected in one of the diagonal branches of said bridge for preheating said cathode to a predetermined emitting temperature, said source being connected in the remaining diagonal branch of said bridge; a high potential source for said discharge device; a high ohmic resistance, said discharge device, said high potential source and said resistance being connected in series, said resistonce being of such value as to produce a voltage drop relatively high as compared to the current therethrough; and means for utilizing the voltage drop supplied from said resistance.

11. in combination, a source of weal; direct current potential, means for setting up controlling currents by said potential of relatively high intensity and for transforming said currents into currents oi relatively high voltage and lovv intensity comprising a discharge tube including a thermionic cathode and an anode; a plurality of impedance devices, said impedance devices forming a balanced bridge system together with said cathode as an arm of said bridge, said potential being applied to a pair 01? diagonal points of said bridge; further means for applying a constant current to the remaining diagonal points of said bridge; a high potential source for said tube; a high ohmic resistance, said tube, said high potential source and said resistance being in series, said resistance being of such value as to produce a relatively high potential drop ascompared to the current therethrough, and a controlled device connected to said resistance.

12. An electrical control system comprising in combination a pairof thermionic discharge tubes each having a cathode and anode electrode; a controlling resistance, the cathode of one of said discharge tubes being connected in series with said controlling resistance; a standard resistance, the cathode of the other of said discharge tubes being connected in series with said standard resistance; a common source of heating current for said tubes, the heating circuits being supplied in parallel from said source; and translating means controlled by the difference of plate current of said thermionic discharge devices.

13. In combination, a source of weak direct current control potential; means for setting up currents by said potential of relatively high intensity; further means for transforming said currents into currents of relatively high voltage and low intensity comprising a discharge device having a thermionic cathode and an anode; a balanced bridge system comprised of impedance arms, said cathode forming part of said bridge system; means for unbalancing said bridgeby heating said cathode from said input potential; a high potential operating source; a high ohmic resistance, said device, said operating source and said resistance being connected in series, said high ohmic resistance being designed to produce high potential drop with low current therethrough;. 

